Vibration damper



April 1 6, 1935. s. ROSENZWEIG 1,998,206

VIBRATION DAMPER Filed May 12, 193 3 2 Sheets-Sheet 1 rvu mm zb frdealPasenzwazj April 16, 1935.

s. ROSENZWEIG VIBRATION DAMPER Filed May 12, 4935 2 Sheets-Sheet 2Patented Apr-.16, 1935 UNITED STATES PATENT OFFICE 1.99am VIBRATION omenseemed Rosenzweig, in; Island City. 1s. 1. Application May 1:, less,Serial No. 01am 4 Claims. (01. 248-16) This invention relates to theelastic suspension or supporting of vibrating bodies, and has generallyin view to provide improved elastic suspension means to prevent orreduce the transmission of vibrations from machines and other vibratingbodies to floors or other foundations on which they are mounted.

According to the. theory the vibration transmissibility of any givenelastic suspension element is best defined as the ratio of thedisturbance produced in a. foundation when the element is used, to thatproduced when the suspended vibrating body is rigidly attached to thefoundation By known formulas the vibration transmissibilitycurves ofelastic suspension elements may be plotted, and such curves show thattransmissibility decreases as the ratio of forced frequency (due to themachine) to the natural frequency of the isolator or suspension elementincreases. When this ratio equals 1.0, or both frequencies are alik of1.41 the curve crosses the unit line indicating that the isolator doesneither harm nor good. on the other hand, the transmissibiiity decreasesvery rapidly as the ratio increases and becomes for instance 02 at aratio of 2.5 for zero damping.

Assumingthatitisdesiredtoscreenthetransmissionofal20cyclehumcausedbyathree phase motor, experience has indicated that aratio oiv 6 1s pox: and

transmissibiiity curves very closely and are perfectly elastic.Therefore they are well suited for useinthesuspension ofvibratingbodies, asalso are such materials as rubber and cork, although rubber,and to a'grcater extent cork, in a measure lacks perfect elasticity.Consequently. when working with these materials a somewhat greater'ratiomustbechosenthanisgiveninthetransmisibility curve'foranideal orperfectly elastic element such as a coiPspring, with the result that,under identical conditions, materials such asrubberandcorkmustbesubjectedfosreater compresion than steel springs.

Insomeinstallationssteelspringsmaybeused more advantageously thanelastic materials such of elastic suspension resonance exists andmaximum vibration is transmitted. At a ratio I combination as rubber andcork.

Accordingly. attempts have been made heretofore to artificially-loadsuch materials as rubber, cork and the like by a vise-like clamping orbolt ing of the same between timbers, steel base elements or the likeand the foundation. This, however, involves costly complications and isimpractical. Moreover, it is impractical to reduce the area ofsuspension materials such as rubber, cork and the like to such an extentthat the loading furnished by the weight of the machine is sumeient tocause the material to have the desired natural frequency.

Accordingly, the general object of the present invention is to providewhat may be termed a balanced vibration damper in which the dampingelement interposed between the machine and its foundation isartificially loaded in a thoroughly practical manner, and in which theexpansive force of the element is balanced by an elastic oppositelyacting force, thus to cause the vibrations of the machine to be mosteffectively absorbed or damped Another object of the invention is toprovide a balanced vibration damper embodying a novel constructionwhereby practically any desired of elastic elements or materials may beemployed.

Another object of the invention is to provide a balanced vibrationdamper embodying a construction whereby the amount of compression. ofthe elastic element may readily be varied and minutely controlled,thereby to provide forobtainingan action of the suited to eachindividual installation. 1

element most ideally with the foregoing and various other objects inview, which will become more fully apparent as the nature of theinvention is better understood, the same consists in the novel featuresof construction, combination and arrangement of parts as will behereinafter more fully described, illustrated in the accompanyingdrawings and vdefined in the appended claims.

In the drawings:

Figure 1 is a transverse section through a vibration damping deviceconstructed in accordance with one practical embodiment of theinvention.

l 'lgure2isayiewsimilartol 'ig. lillustrating an alternative embodimentof the invention.

Flgure3isaviewsimilartoFigs. 1 andzillustrating anotheralternative'embodiment of the invention; and

Figure 4 is a diagram illustrating the action of the device.

Referring to the drawings in detail, A in each of Figs. 1 to 3designates generally a base which -is suitably formed to be fastenedsecurely and rigidly to a foundation, while B-designates generally apreferably inherently rigid member which is suitably formed to have themachine or other vibrating body fastened thereto, and which is supportedby the base A through the instrumentality of an interposed, artificiallyand elastically loaded elastic element designated generally as C.

Referring particularly to the embodiment of the invention illustrated inFig. l of the drawings, it will be observed that the rigid base A is ofhollow construction embodying an open-top channel formation having abottom wall II and upwardly and inwardly directed side walls II, andthat depending from the said channel formation are legs or continuationsof the side walls thereof, designated as II, which are suitably formedto be engaged against and to be rigidly fastened to a foundation thus tosupport the channel formation with its bottom wall ill in spacedrelation thereto.

Referring further to Fig; 1, it will be observed that the member B is ofopen-bottom channel form and comprises a plate I! having a medial,threaded socket formation designated as II, and downwardly and outwardlydirected side walls designated as It. The external width of this memberis suitably less than the internal width of thechannel formation of thebase A, preferably of such less width that it may readily be insertedinto the latter channel formation through the open top thereof, and theside walls I! of said member preferably have the same inclination as theside walls I I of the base channel formation. However, both the width ofthe member B and the inclination of its side walls may vary considerablyas compared with the width of the base channel formation and theinclination of its side walls.

Still referring to Fig. l of the drawings, it will be observed that theelastic element C interposed between the member B and the base A isillustrated as being comprised by a block of cork shaped to fit saidmember B and to extend below the free or bottom edges of the side wallsI! thereof.

Knowing the necessary loading or compression of the block C to have adesired natural vibration frequency for a given installation, artificialloading of said block may be effected and maintained by firstcompressing the same in any suitable manner between the member B and thebottom wall ll of the base channel formation and thereafter insertingelastic strips I of cork, rubber or the like between the inclined sidewalls H and I5, said strips, because of the inclination of saidsidewalls, serving to elastically key or look the block C in a compressedcondition between the member B and-the base A so that it may have adefinite amount of upward or outward movement.

The construction so far -described obviously may be used as an elasticsuspension or support 'formofcoilsprings. Fig.3

initialcompression of without other elements, in which event provisionfor moimting the base A "with the bottom wall ll of its channelformation in spaced relationship to the formation manifestly is However,to obtain most satisfactory results and to provide a balanced damper inwhich the elastic element C is maintained elastically loaded, a secondelastic element D is combined with the element C to function counterthereto.

According to the construction illustrated in Fig. 1, the second elasticelement also is in the form of a block of cork and is interposed betweenthe under side of the wall I. and a plate I! which is spaced therebelow.The plate II, the block D and the wall II are provided with alinedopenings II, I and 2|, respectively, and through these openings extendsa bolt 2| which has its threaded end engaged in the threaded socketformation It and its head 22 cooperating with the under side of theplate ll. Consequently, by manipulation of said bolt the blocks C and Dmay be loaded and their loading may be minutely controlled, and,moreover, the block D serves to maintain the block C elastically loadedand balanced.

Obviously, the base A may be of any desired length and the blocks C andD as well as the member B and the plate ll may be coextensve in lengththerewith, and a plurality of bolts 2| may be employed or,alternatively, short blocks C and D may be located at desired intervalsalong the base. In this connection, and as indicated by Fig. 2 of thedrawing it obviously is not necessary tohave the side walls II and I! ofthe base A and the member B inclined and to have the strips l8 interpomtherebetween if the block D and the bolt 2| are employed in thecombination. on the contrary, the said sidewalls It and I under suchconditions may be disposed vertically or may be entirely eliminated, asalso may the strips II. I

Referring to Fig. 2 of the drawings, it will be observed that theconstruction is subdantially thesameasillustraiedinl 'lg.lwlththeexcep-'tion that the member B lacks side walls and the side walls of thechannel formation of the base A are vertical, and that the elasticelement D is inthe formofacoilspring. Asa further modification of theconstruction illustrated in Fig. 1, Fig. 2indicatesthattheboltfl'mayberigidwith the member 3 and that it may have threaded, adjustableconnection with theplate l1.

Referringto Fig.3ofthedrawinssitwill be observed that the constructionand combination is, to all-intents and purposes, the same as illustratedin Figs. 1 and 2 with the exception that theelastic elements'CandD'bothareinthe also illustrates that thebaseAmaytaketheformofaflatplatethat thefoundationmay-berecessedtotetheelastlcelementDorDZandthattheboltll-mayextendlooselythroughthebase,thememberBandtheplate l'l'andmayhaveitsheadfl withthememberBanditsnut u' cooperating with the plate Il .Theaction ofthedeviceis illustrated in Fig. 4 of the drawings wherein theline X represents the total travel or permissible loading or compressionof the elastic element'C, the'line Y represents loading or compressionof said element C, and the line Z represents loading or compression of'the elastic element D or D. If the initial compression given to theelement C equals Y", spring curves as indicated by the lines I, landlresult..0ntheother hand,ifthe element C isas indicated as-l by the lineY1, spring curves as indicated byv the lines I, I and 2' result.

To further illustrate the action, let it be assumed that the elasticelement C has an initial compression equal to Y. If the balancingelastic element D or D is made of exactly the same. dimensions aselement C, its initial compression must be the same as Y. The springcurves are alike but oppose each other. The resultant forces areparallel to each other or, in other words, when a load is put on elementC all resultant forces are alike.

When Y is or the total permissible travel or compression of the elementC, element D or D gives up its potential energy in a point a asindicated. If the initial compression is less than 50% curve I willcross curve I and from there on follow the latter curve, since element Dor D' has given up all of its energy and after point a has been reachedwill have no further function.

The important result taught by the diagram is that no matter how greatmay be the initial compression given the elastic elements, the functionsof said elements are all alike and being parallel to each other theirloadings are increased in identical manner. I

The action of the present damper, as tests have shown, is instantaneousunder the slightest impacts, and on account of its balanced arrangementit acts equally well in either direction.

Moreover, the fact that it can be minutely ad-- dusted and that anyamount of added compression to its elastic elements does not affect itspredetermined action is especially advantageous. Without furtherdescription it is thought that the features and advantages of theinvention will vibrating body fastened thereto, an elastic elementinterposed between said member and the adjacent side of said wall, asecond elastic element disposed at the other side of said wall, tensionmeans connecting said elastic elements and maintaining them undercompression against said wall, said tension means being freely movablerelative to the wall to permit either elastic element to be furthercompressed and the other to correspondingly expand, the base furtherhaving an abutment disposed outwardly relative to said. member, and anelastic element interposed be tween said member and said abutment.

2. A vibration dampercomprising a base to be fastened -to a foundation,said base having a wall provided with an opening, a member at one sideof said wall to have a vibrating body fastened thereto, an elasticelement interposed between said member and the adjacent side of saidwall, a second elastic element disposed at the other side of said wall,a tension rod extending loosely through said'elastic elements andloosely through the opening in said wall and cooperating at its endswith said member and the second mentioned elastic element, respectively,to maintain said elastic elements normally compressed and to permiteither elastic element to be further compressed and the other tocorrespondingly expand, means whereby the efie'ctive length of said rodmay be varied to vary the amount of compression of said elasticelements, the base having an abut- 'ment disposed outwardly with respectto said -member, and an elastic element interposed between said memberand said abutment.

3. A vibration damper as set forth in claim 1 in which the abutment isconstituted by an inwardly and mentioned elastic element and its otherend threaded into the member.

SIEGFRIED BOSENZWEIG. V I

